1. Field of the Invention
The present invention relates to a flat rack container, and more particularly, to an integral buffering apparatus disposed between end walls and a base and for automatically controlling a flow rate of oil that flows in a cylinder housing through channels formed in a slider when the end walls are folded, to control a falling speed of the end walls, thereby absorbing an impact of the end walls, preventing damage of the end walls and the base, and ensuring safety of a worker.
2. Description of the Related Art
In general, containers are used to conveniently transfer goods and their sizes are standardized by the International Organization for Standardization (ISO), e.g., 20 feet, 40 feet, and 45 feet.
Examples of containers include dry containers, reefer containers, open top containers, and flat rack containers.
From among these, flat rack containers do not have ceilings and side walls and thus medium-sized goods such as cars or machines may be loaded or unloaded from both sides.
FIG. 1 is a perspective view of a conventional flat rack container 10.
As illustrated in FIG. 1, the conventional flat rack container 10 includes a base 11 on which goods are loaded, and an end wall 13 rotatably combined at each of two sides of the base 11.
The end wall 13 is combine with the base 11 by using a pivot (or hinge) 14, and may rotate about the pivot 14 to be folded or unfolded.
A counter balancing spring 15 for elastically supporting rotation of the end wall 13 is disposed under the end wall 13.
A first locker 16 for maintaining an unfolded state is disposed at one side of the end wall 13, and a second locker 17 for maintaining a folded state is disposed at another side of the end wall 13.
When the conventional flat rack container 10 is used, the end wall 13 is maintained in the unfolded state (a perpendicularly lifted state, represented by solid lines in FIG. 1) and the first locker 16 is locked to fix the position of the end wall 13.
On the other hand, when the conventional flat rack container 10 is not used or is being transported, the end wall 13 is maintained in the folded state (a horizontally laid state, represented by virtual lines) and the second locker 17 is locked to fix the position of the end wall 13.
In most cases, the end wall 13 is very heavy, e.g., about 400 to 450 kg. Accordingly, when the end wall 13 is folded, a resistive force has to be applied to the end wall 13 so as to slow rotation of the end wall 13 about the pivot 14. The counter balancing spring 15 applies such a resistive force to the end wall 13 to buffer an impact of the end wall 13 that the end wall 13 may fall on the base 11 slowly without an impact.
However, in the conventional flat rack container 10, the counter balancing spring 15 applies to the end wall 13 a force acting upward, and thus the end wall 13 may be lifted due to wind or an impact on the road while the conventional flat rack container 10 is being transported by a car and the end wall 13 may crash into a bridge pier or the like. In order solve this problem, the force acting upward to lift the end wall 13 is suppressed by using a spring having a tensile force that is not sufficient for counter balancing. However, in this case, a resistive force applied to the end wall 13 when the end wall 13 is folded is excessively weak. Accordingly, the end wall 13 applies a strong impact to the base 11 when the end wall 13 falls on the base 11 and thus the lifespan of the conventional flat rack container 10 is reduced. In addition, the impact may cause various safety accidents involving workers and thus safety of the workers is not ensured.
Currently, a technology using a powered hydraulic cylinder instead of a counter balancing spring is suggested. However, in this technology, electricity is supplied to drive a motor and power of the motor is used to operate the powered hydraulic cylinder. Accordingly, electrical equipment is additionally required, operation is inconvenient, and manufacturing costs of a flat rack container is increased.